In recent years, a valve timing control apparatus configured to allow varying of opening and closing timings of an intake valve and an exhaust valve depending on an operational condition of an internal combustion engine is often mounted to one terminal end of a cam shaft.
According to one known technique relating to one type of valve timing control apparatus of the above-noted kind, in a valve timing control apparatus configured to transmit an engine rotational drive force from a crank shaft to the cam shaft via a power transmitting means such as a timing chain, when no pressure oil is being fed to a hydraulic chamber from a pump at the time of startup of the engine, a leading end of a stopper piston (lock pin) is brought into engagement into a stopper hole (receiving hole), thereby to lock a shoe housing (outer rotor) and a vane rotor (inner rotor) relative to each other for their rotation in unison, as a result of which generation of hitting noise between the housing and the vane component is avoided (see e.g. Patent Document 1).
According to another known technique relevant to the above, an arrangement is provided such that at the time of startup of an internal combustion engine, upon establishment of synchronization or positional registry between a receiving hole and a retracting hole, an amount of fluid is fed into an advanced angle chamber through a first fluid passageway or into a retarded angle chamber through a second fluid passageway Further, at the time of the synchronization of positions between the receiving hole and the retracting hole, a third fluid passageway is communicated to the first fluid passageway or the second fluid passageway; whereas at the time of non-synchronization therebetween, the communication between the third fluid passageway and the first or second fluid passageway is blocked. For use in this construction, there is disclosed a technique for restricting generation of noise due to “fluttering” of the lock pin within the retracting hole in association with pressure fluctuation, thus restricting frictional wear of the lock pin (see e.g. Patent Document 2).
According to still another known technique relevant to the above, a phase holding mechanism (a lock pin, a spring) is provided for holding a rotational shaft (a cam shaft and an inner rotor) and a rotation transmitting member (an outer rotor) at a predetermined relative phase when the internal combustion engine is under a valve opening/closing phase when the engine can be started, at the time of an intermediate relative phase between the most advanced angle phase wherein the volume of the retarded angle chamber is rendered minimum by the vane and the most retarded angle phase wherein the volume of the advanced angle chamber is rendered minimum by the vane. Further, a relative rotation restricting means (an engaging pin, a spring, an engaging groove) is provided for restricting relative rotation of the rotational shaft from the predetermined phase relative to the rotation transmitting member toward the retarded angle side, at the time of stopping and starting of the internal combustion engine. With these arrangements, generation of hitting noise of the vane at the time of startup of the internal combustion engine and engine startup failure are prevented reliably and at the same time the arrangements provide an increased variable control range (see e.g. Patent Document 3).